1. Technical Field
The technical field relates to a camera system, and more particularly relates to a system used in digital single lens reflex cameras of the interchangeable lens type.
2. Description of the Related Art
Digital single lens reflex cameras with which an optical image of a subject can be converted into an electrical image signal and outputted have rapidly grown in popularity in recent years. With these digital single lens reflex cameras, when the user looks through the viewfinder to view a subject, the light that is incident on the imaging lens (that is, the subject image) is reflected by a reflecting mirror disposed along the imaging optical path beyond the lens, and this changes the optical path to go through a pentaprism or the like and obtains a positive image that is guided to the optical viewfinder, allowing the subject image that has passed through the lens to be seen through the optical viewfinder. Therefore, the position where the viewfinder optical path is formed is usually the home position of the reflecting mirror.
Meanwhile, when a lens is used for imaging, the reflecting mirror instantly changes its position, and is retracted from the imaging optical path, which switches the viewfinder optical path to the imaging optical path, and instantly returns to its home position as soon as imaging is complete. This method is common to a conventional film camera and a digital camera.
One of the features of a digital camera is that an image can be captured while the user looks at a display device (such as a liquid crystal monitor), and the captured image can be checked right after it is captured. However, when a conventional single reflex lens reflecting mirror is used, a liquid crystal monitor cannot be used during image capture. This means that image capture cannot be performed using a liquid crystal monitor, and the user instead has to look through the viewfinder, and this makes the camera very difficult to use for a novice who is inexperienced with digital camera photography.
In view of this, a digital single lens reflex camera has been proposed with which images can be captured while the user looks at a liquid crystal monitor, for example (see Japanese Laid-Open Patent Application 2001-125173, for instance).
Also, in recent years consumers have wanted digital single lens reflex cameras that are not only capable of capturing still pictures, but also have functions such as capturing moving pictures.
With the digital single lens reflex camera disclosed in Japanese Laid-Open Patent Application 2001-125173, however, the capture of moving pictures is not taken into account, so even if an interchangeable lens that is compatible with moving picture capture is mounted to the camera body, it may still be impossible to capture moving pictures, which is inconvenient to the user.